Flexible mold ice maker control

ABSTRACT

Energization of a thermostat reset heater for a flexible mold ice maker is controlled in accordance with the application of vacuum and pressure to the flexible mold so that premature termination of harvesting and fill operation is avoided. Energization of the reset heater is also controlled in accordance with the level of ice cubes in the receiving bin, and in accordance with the bin position.

United States Patent 1 Learn et al.

FLEXIBLE MOLD ICE MAKER CONTROL June 19, 1973 Primary Examiner-WilliamE. Wayner Assistant Examiner-William E. Tapolcai, Jr. Attorney- F. H.Henson and E. C. Arenz [73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Sept. 24, 1971 [57] ABSTRACT [21] Appl- 183,433 Energizationof a thermostat reset heater for a flexible v mold ice maker iscontrolled in accordance with the ap 52 vs. C]. 62/135, 62/353 plicationof vacuum and P to the flexible mold 51 Int. Cl. F25c 1/06 so thatPremature termination of harvesting and fill P' 53 Field f Search62/137, 135 353; eration is avoided. Energization of the reset heater is137/624 l8 also controlled in accordance with the level of ice cubes inthe receiving bin, and in accordance with the [56] References Cited binPosition- T ED STATES PATENTS 7 Claims, 7 Drawing Figures 3,388,5606/l968 Moreland 62/353 so 2Q w x "J "J I W U 51.. Pin up 64 4 t 20 44 7-Zmo $262 a 60 3 74- 5s 50 54 5B 66;

PAIENIED JUN I 9 I075 SREEIZNG PATENIEU JUN 9 973 sum 3 or 4 1111111111IIIIIIIIIIIIIIIIII I 1111111111! PAIENTED sum b N 4 ELECTRIC AIR PUMPJIIIIIIIIIIIIIIIIIIIIIIJ[IL/1 I I I I I f I I I I I I I I I I I I f I ff I J If? FLEXIBLE MOLD ICE MAKER CONTROL CROSS-REFERENCE TO RELATEDAPPLICATION U.S. Pat. application Ser. No. 874,598 filed Nov. 6, 1969,now U.S. Pat. No. 3,648,732 discloses a pneumatic ice maker andself-advancing programmer of a currently preferred character with whichthis invention may be employed.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionpertains to the art of controlling flexible mold ice makers in which themold is inverted to eject the cubes and then is restored to a positionto receive water for a subsequent batch of cubes.

2. Description of the Prior Art The use of a reset heater with athermostat to control starting and stopping the operation during whichice is harvested and the cube cavities are filled with water inautomatic ice makers of various types'is well known. Examples of resetheaters used with thermostats in automatic ice makers of the hydraulictype are disclosed in U.S. Pat. Nos. 2,770,102 and 3,388,560.

The manner in which the thermostat and reset heater function willbeexplained in general terms to aid in understanding the distinctivecharacter of the present invention. The thermostat performs the functionof starting and stopping the harvesting and fill operation (hereinaftercalled operation).'The thermostat is located in a position to beresponsive to temperature changes of the contents of the cube cavities.As water in the cube cavities cools down and freezes, the thermostatwill correspondingly cool down. When the thermostat reaches its triptemperature of, say, to F below the freezing temperature, the thermostatcauses its associated switch to close. This starts the harvesting partof the operation, which automatically takes place, and is followed bythe fill part of the operation during which water is introduced to thecube cavities of the tray. Under normal conditions, the water issufficiently warm to reset the thermostatic switch to an open positionafter a short period of time, thereby stopping the operation. However,to assure reset under a condition when extremely cold water is admittedto refill the tray, a heater has typically been added which is in heatexchange relation with the thermostat. If this heater is controlled onlyby the thermostat (i.e., it is energized when the thennostatic switchcloses and deenergized when the thermostatic switch opens) the wattageof the heater and thermal impedance between the heater and thermostatbecome rather critical. Too high a wattage can reset the thermostatbefore the operation is complete, and too low a wattage is insufficientto reset the thermostat if the tray has been soaking for an appreciabletime in an exceptionally low temperature freezer. Line voltagevariations may also affect the operation because they contribute largepower changes to the heater.

It is to the solution of the above-noted problems of obtaining properreset of the thermostat in a flexible mold ice maker that the inventionis in part directed.

SUMMARY OF THE INVENTION In accordance with one aspect of the invention,a switch for controlling the reset heater is operated to a positionenergizing the reset heater only when the flexible mold is subjected toavacuum condition. In my currently preferred type of flexible moldautomatic ice maker, in which a vacuum is applied to condition the moldto receive water for each subsequent batch of cubes, the major part ofthe on time of the reset heater occurs at the end of an operation, sothat reset of the thermostat is assured without any appreciablelikelihood of a premature reset of the thermostat. With this timingsequence, the wattage for the reset heater may be chosen to be highenough to reset the thermostat under the worst conditions anticipated.

The invention contemplates providing means responsive to the volume ofice cubes stored in the cube re ceiving bin and being operativelyconnected to the reset heater switch means to maintain the switch meansin a position energizing the reset heater in response to a build-up ofice volume beyond a predetermined level. The arrangement also lendsitself to incorporating means responsive to the removal of the bin froma normal ice receiving position to operate the switch means to theposition in which the reset heater is maintained energized.

DRAWING DESCRIPTION FIG. 1 is a vertical sectional view of anarrangement for carrying out the invention and. illustrating theposition of the parts during the period between successive operations;

FIG. 2 is a vertical sectional view of a fragmentary portion of theparts of FIG. 1 and showing the parts in the positions they assume whenthe flexible mold is subject to a vacuum condition and in which furtherproduction of cubes is indicated;

FIG. 3 is a view similar to FIG. 2, but showing the position of theparts when an adequate quantity of cubes is available and furtherproduction is to be halted;

FIG. 4 is a view similar to FIG. 31, but showing the position of theparts while a batch of cubes freezes and with further harvesting beingprecluded until some of the cubes have been removed from the bin;

FIG. 5 is a view similar to FIG. 4 but showing the position of the partswhile the bin is removed from its proper cube receiving position;

FIG. 6 is a schematic view of the circuit arrangement and basicconnections between a programmer, pump, and the tray; and

FIG. 7 is a vertical sectional view of an arrangement which providesautomatic shut-off of ice making when the bucket is full of cubes and inwhich the weight of ice cubes provides the signal for shut off.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention can be carriedout in connection with any automatic ice maker having a flexible moldand to which a vacuum is applied after cube ejection to place the moldin condition to receive water for a subsequent batch of cubes. However,the inventionwill be de scribed in connection with an arrangement asdisclosed in U.S. Pat. application Ser. No. 874,598, which is thecurrently preferred system as presently contemplated, and to whichreference should be had for a full description of a harvesting and filloperation. For present purposes, it will suffice to note that thepneumatic programmer 10 of FIG. 6 is powered by an electric air pump 12connected thereto by the suction and pressure lines 14 and 16. The line18 represents the line which provides either suction or pressure to thetray 20 while the line 22 represents the line which furnishes water tothe tray.

Referring to FIG. 1, the tray and its associated parts, along with theunderlying ice receiving bin 24, are all located in a freezercompartment 26 having a rear wall 28 to which the rigid tray 20 isfixedly secured.

The space 30 between the rigid tray 20 and the flexible bladder or mold32 is in communication with the line 18 connected to the pneumaticprogrammer 10. The mold is formed so that with neither pressure norvacuum in the space 30 it assumes the form shown in FIG. 1 in whichindividual cube cavities are presented. When a vacuum is applied to thespace 30, the mold assumes the form shown in FIGS. 2 and 3. When thespace 30 has adequate pressure applied thereto, the mold is inflated(not shown) to invert the cube cavities and eject the ice cubes into thebin. The thermostat assembly 34 (FIGS. 1 and 6) is secured to the tray20 and is located in the space 30 in a position of good heat exchangerelation with the bottom of one of the cube cavities. The thermostatassembly includes the thermostatically controlled switch 36 as well as areset heater 38 in good heat exchange relation with the temperatureresponsive part of the thermostat. The switch 40 which controls thereset heater is of the leaf type and is shown in end view in FIG. 1. Theopposite end of the switch 40 is supported by structure attached to therigid tray 20.

Two actuator diaphragm assemblies 42 and 44 are shown in FIG. 1. Sincethe parts of each are for the most part the same, the parts of only onewill be described in some detail. The chamber 46 ofeach is incommunication with the space 30 between the tray and mold, and is sealedby a flexible diaphragm 48 which has a stem 50 secured thereto formovement therewith and which is biased downwardly by a compressionspring 52 to the normal at-rest position as shown in I FIG. 1. One endof an actuating arm 54 is secured to the bottom end of the stem of theright assembly 44 while an intermediate part of the arm is secured tothe bottom of the stem of the left assembly 42. The free end 56 of theactuator arm is located to be moved upwardly into a position engagingthe reset heater switch in accordance with the pressure of suctionconditions controlling the diaphragm assemblies.

A cube level sensing arm 58 is also associated with the right diaphragmassembly 44. At point 60 the sensing arm is pivotally secured tostructure connected to the rigid tray to provide a fixed pivotallocation for the arm. At point 62 the one end of the sensing arm ispivotally secured to the stem of the right diaphragm assembly 44 toprovide a movable pivot location.

A latch 64 for the reset heater switch 40 is fixed to the underside ofthe tray 20. It is positioned so that the lower hook shaped end of thelatch will hold the switch 40 closed when the free end 56 of theactuating arm lifts the lower leaf of the switch 40 sufficiently high asshown in FIG. 3. This occurs under a condition of an adequate height ofcubes being sensed by the sensing arm 58.

The arrangement according to the invention also includes a reset arm 66which functions in accordance with the bin 24 position and can operateagainst both the latch 64 and the reset heater switch 40 as will beexplained in connection with FIGS. 4 and 5. The reset arm is pivotallyfixed at point 68, has a lower end portion adapted to be engaged by theupper rear edge of the bin 24 when the bin is in a proper ice receivingposition, and has an upper end which includes the latchengaging-face 70and an off-set switch-engaging-face 72. A compression spring 74 biasesthe reset arm 66 in a counterclockwise direction.

OPERATION (FIGS. 1-6) The cold air in the freezer cools the waterpreviously discharged into the cube cavities of the flexible mold 32,and ice cubes are formed. The thermostat 34, being heat stationed closeto the bottom of one of the cube cavities, senses the cube temperatureand is designed to close its switch 36 on a drop in temperature to apoint of, say, between 12 to 20F. A temperature in this range isconsidered to provide sufficient sub-cooling below the freezing point ofwater to make sure that the cubes in all the othercavities are alsofrozen.

Closure of the contacts of the thermostatically controlled switch 36completes the circuit through lines 76 and 78 (FIG. 6) to energize theair pump 12 and thereby initiate the harvesting and till operation. Theprogramming valve 10 controls the system from this point to the end ofthe operation in a fashion described in detail in the earlier notedpatent application. In accordance therewith, a suction is first drawn inthe space 30 for a relatively short period of time, typically 15 to 20seconds, to provide a prestripping action as the mold is drawn downagainst the tray by the suction and peeled away from the cubes. The formof the mold in this condition is illustrated in FIG. 2. The actuatordiaphragm assemblies 42 and 44 are also displaced upwardly byatmospheric pressure as shown in FIG. 2 and accordingly pull the sensingarm about its pivot 60 to the position shown in FIG. 2, assuming thatthe level of cubes is as shown in FIG. 2 so that the cubes do notobstruct full movement of the arm. The actuating arm 54 is pulledupwardlyito the location as shown in FIG. 2 to close the reset heaterswitch 40 to thereby energize the reset heater 38 through completion ofa circuit including the heater and switch as shown in FIG. 6. Thewattage of the reset heater 38 is selected so that it it takes asubstantially longer time of heating to reset the thermostat from itstrip temperature to its reset temperature than the time taken forprestripping. For example, in the general arrangement shown, a heaterwattage of 1.5 watts requires approximately 2 minutes to reset thethermostat. Since the prestripping operation normally taken less thanhalf a minute, the programming valve will move to the next position longbefore the reset of the thermostat and the operation will continue byconverting the vacuum condition to a pressure condition in the space 30.

With an adequate pressure, the mold is inflated to invert the cubecavities and thus eject the cubes. Upon the change from vacuum topressure, the actuator diaphragm assemblies return by the force of thecompression springs 52 to the positions shown in FIG. 1. As such, thereset heater switch contacts 40 have opened and the reset heater is nolonger energized. As the operation proceeds beyond cube ejection, theprogram mer valve 10 advances further to a position in which theflexible mold is deflated.

At the end of the deflation, a vacuum is again applied to the tray space30 to assure a complete return of the mold to a FIG. 2 position. Thevacuum operated water valve associated with the programmer is operatedat this time so that water fills the batch chamber associated with theprogrammer valve in approximately 5 to seconds. During thisshort period,the actuator diaphragm assemblies, actuator arm and sensing arm willhave again assumed the position shown in FIG. 2 with the reset heaterswitch 40 closed (again assuming as before that no cubes interfere withthe movement of the I sensing arm 58). The programmer valve continuesits advance and releases the vacuum in the tray space 30 so that theparts return to the FIG. 1 position.

Water is then forced from the batch valve up to the cube cavitiesthrough the water line 22 and discharge tube 80. The programmer thenadvances to its final position in which the water remaining in the line22 returns to the batch valve and a vacuum is again applied to the trayspace 30. The parts again take a FIG. 2 position. After a short period,the water in the cavity in conjunction withthe energized reset heater 38will cause the thermostat 34 to reset by opening the thermostatic switchcontacts 36. This turns off the air pump 12. The pressures in the systemthen equalize and the actuator diaphragm assemblies and associated partsreturn to the position shown in FIG. 1. When the water subsequentlyfreezes, the thermostatically-controlled switch 36 will again close andanother harvesting and fill operation will start.

It will be appreciated from the foregoing that so long as the cubereceiving bin 24 is not removed, and so long as the level of cubestherein does not reach a level in which the downward pivoting of thesensing arm 58 is restricted, the operation of the parts will be as inFIGS. 1 and 2 only.

After the cube level builds up to a position in the bin such as shown inFIG. 3, when the sensing arm 58 swings down its movement is blocked bythe cubes and is accordingly prevented from completing its normal swing.This in turn prevents the right actuator diaphragm assembly 44 fromcompleting its normal upward displacement. Since the left actuatordiaphragm assembly is not so inhibited, the actuating arm 54 tilts asshown in FIG. 3 so that the free end 56 of the arm forces the switchleafs 40 sufficiently above their normal closed position that the hookof the latch 64 snaps over under the lower leaf to hold the switchclosed irrespective of the position of the actuator arm 54. As theprogramming valve continues its advance the actuator diaphragmassemblies return to their initial positions as in FIG. 4 but the switch40 contacts are held closed by the latch 64. In this way, power issupplied continuously to the reset heater and the thermostat isprevented from starting another harvesting and fill operation eventhough a fill occurs and a new batch of cubes are frozen. Thus, thesystem is maintained in the off condition by preventing the thermostatfrom being cooled down to its trip temperature.

The manner in which the system is restored to normal operation byremoval of the ice bin 24 and removal of ice cubes therefrom will bedescribed principally in connection with FIG. 5. When the user moves thebin 24 forwardly, the compression spring 74 causes the reset arm 66 topivot counterclockwise to the position shown in FIG. 5. As such, thelatch engaging face 70 of the arm moves the latch 64 from its positionholding the switch 40 closed. However, the switch engaging face -72 ofthe reset arm engages the switch 40 to hold it closed. Thus, if the binis either removed from the freezer, or is not fully returned to itsproper position,

the ice maker will be prevented from starting a harvesting operationbecause of the closed switch 40. When the bin 24 is pushed back into itsproper position, it engages the lower end of the reset arm 66 and pivotsit back to the position shown in FIG. 1 so that the switch will open anddeenergize the reset heater. Subse quent cooling of the thermostat toits trip point can then initiate another operation.

The use of the vacuum condition to control the switch for the resetheater may be employed whether prestripping is provided or not. Theprestripping operation being relatively short does not adversely affectthe operation of the system. However, it is conceivable that withimproved mold materials a prestripping operation may not be required, inwhich case the reset heater is first energized only when the mold isdrawn back into a water receiving condition.

ALTERNATIVE ARRANGEMENT The arrangement in FIG. 7 illustrates howautomatic shut off may be obtained in another fashion when the fin isfull of cubes. In this case a single actuator diaphragm assembly 82 isused and the reset heater switch 40 is incorporated in the tray space30. The actuator diaphragm assembly is essentially the same as those ofFIGS. 1-5. A lever 84 is pivoted on a bearing 86 mounted on the support88 which is in turn attached to the back wall of the freezercompartment. A forked forward end of the lever 84 is held captive by thelower end of the actuator stem. Thus, .as the diaphragm moves up anddown during the operation in accordance with vacuum and pressureconditions in the space 30, the lever 84 is forced to move also. Theback end of the bin 90 has a ledge 92 supported by the rear end of thelever 84. The ice bin 90 is arranged with a front foot 94 which restsupon a shelf in the freezer compartment. The bin pivots around thisfront foot in accordance with the weight of the ice cubes in the bin.Thus, the

weight of the ice cubes will work in opposition to the force of thecompression spring 52 in the actuator diaphragm assembly. The operationof the arrangement of FIG. 7 will be in general terms the same as theoperation of the arrangement of FIGS. 1-5 so far as the application ofpressure and vacuum to the tray space 30 result in the actuatordiaphragm assembly responding and controlling the operation of the resetheater switch 40. However, if the weight of the ice cubes in the bucketreaches a predetermined amount, the lever 84 will be pivoted and held ina counterclockwise pivoted position such that the switch 40 remainsclosed even though no vacuum exists in the space 30. In the same fashionas described heretofore, this prevents the thermostatfrom closing for asubsequent operation until sufficient ice cubes have been removed toreduce the weight thereof to an amount that further harvesting of icecubes is indicated.

The schematic, of FIG. 6 is applicable to both arrangements describedherein.

A manual on-off switch may be placed in the circuit to prevent operationof the air pump, or a switch may be placed in parallel with the resetheater switch 40 to provide manual on-off control in that fashion.

What we claim is:

1. In a flexible mold ice maker of the type having a harvesting and filloperation in which pressure is applied to invert the mold and eject thecubes into a bin, and a vacuum is then applied to condition the mold toreceive water for a subsequent batch of cubes, a control arrangementincluding:

a thermostat subject to the heat of the contents of the mold andoperable to initiate said harvesting and fill operation in response to atemperature depression corresponding to the contents being adequatelyfrozen, and to terminate the cycle in response to a temperature risecorresponding to the receipt of water of normal temperature into themold;

heater means in heat exchange relation with said thermostat to insuresensing a temperature rise by said thermostat;

switch means for controlling energization of said heater means; and

means in communication with the space to which said pressure and saidvacuum applied and movable in accordance with the application of saidpressure and said vacuum for effecting operation of said switch means toa position energizing said heater means in response to the applicationof said vacuum.

2. In an ice maker according to claim 1:

means responsive to the level of cubes in said bin an arranged tomaintaining said switch means in a position energizing said heater meansin response to a build-up cubes beyond a predetermined level.

3. In an ice maker according to claim 1:

means responsive to removal of said bin from a normal cube receivingposition for placing said switch means in a heater means energizingposition.

4. In an ice maker according to claim 1 wherein:

said switch operating means comprises a pair of movable diaphragmassemblies carrying means for engaging said switch means; and

cube level sensing means responsive to the level of cubes in said binand being connected to one of said diaphragm assemblies to restrict themovement of said one diaphragm assembly when the cubes-exceed apredetermined level.

5. In an ice maker according to claim 1 including:

a pair of diaphragm assemblies carrying a switch actuating arm and beingmovable for substantially the same distance under normal conditions inresponse to said vacuum condition; cube level sensing means connected toone of said diaphragm assemblies to restrict the movement of said onediaphragm assembly in response to a cube level above a predeterminedlevel so that a switch engaging end of said actuator arm moves saidswitch beyond its normally closed position; and

latch means for holding said switch beyond said normally closed positionupon the return of said diaphragm assemblies to their normal position inthe absence of said vacuum condition.

6. In an ice maker according to claim 5 including:

reset arm means movable in accordance with positioning of said bin andoperable to disengage said latch means from said switch means upon theremoval of said bin and to maintain said switch means closed, until saidbin is subsequently replaced in its normal ice receiving position.

7. In a pneumatic ice maker in which a harvesting and fill operationtakes place in accordance with energization of means subjecting a spaceclosed by a flexible cube mold to vacuum and pressure conditions," acontrol arrangement including:

thermostatic means responsive to a temperature corresponding to awell-frozen condition of said ice to energize said means for subjectingsaid space successively to a vacuum, pressure, and vacuum condition, andresponsive to a temperature above freezing corresponding to a supply ofwater of normal temperature to said mold to deenergize said means; 7

reset heater means energizable to apply heat to said thermostat;

switch means for controlling energization of said reset heater means;and

means for operating said switch means to a position energizing saidheater means only when said vacuum condition exists.

1. In a flexible mold ice maker of the type having a harvesting and filloperation in which pressure is applied to invert the mold and eject thecubes into a bin, and a vacuum is then applied to condition the mold toreceive water for a subsequent batch of cubes, a control arrangementincluding: a thermostat subject to the heat of the contents of the moldand operable to initiate said harvesting and fill operation in responseto a temperature depression corresponding to the contents beingadequately frozen, and to terminate the cycle in response to atemperature rise corresponding to the receipt of water of normaltemperature into the mold; heater means in heat exchange relation withsaid thermostat to insure sensing a temperature rise by said thermostat;switch means for controlling energization of said heater means; andmeans in communication with the space to which said pressure and saidvacuum applied and movable in accordance with the application of saidpressure and said vacuum for effecting operation of said switch means toa position energizing said heater means in response to the applicationof said vacuum.
 2. In an ice maker according to claim 1: meansresponsive to the level of cubes in said bin and arranged to maintainingsaid switch means in a position energizing said heater means in responseto a build-up cubes beyond a predetermined level.
 3. In an ice makeraccording to claim 1: means responsive to removal of said bin from anormal cube receiving position for placing said switch means in a heatermeans energizing position.
 4. In an ice maker according to claim 1wherein: said switch operating means comprises a pair of movablediaphragm assemblies carrying means for engaging said switch means; andcube level sensing means responsive to the level of cubes in said binand being connected to one of said diaphragm assemblies to restrict themovement of said one diaphragm assembly when the cubes exceed apredetermined level.
 5. In an ice maker according to claim 1 including:a pair of diaphragm assemblies carrying a switch actuating arm and beingmovable for substantially the same distance under normal conditions inresponse to said vacuum condition; cube level sensing means connected toone of said diaphragm assemblies to restrict the movement of said onediaphragm assembly in response to a cube level above a predeterminedlevel so that a switch engaging end of said actuator arm moves saidswitch beyond its normally closed position; and latch means for holdingsaid switch beyond said normally closed position upon the return of saiddiaphragm assemblies to their normal position in the absence of saidvacuum condition.
 6. In an ice maker according to claim 5 including:reset arm means movable in accordance with positioning of said bin andoperable to disengage said latch means from said switch means upon theremoval of said bin and to maintain said switch means closed, until saidbin is subsequently replaced in its normal ice receiving position.
 7. Ina pneumatic ice maker in which a harvesting and fill operation takesplace in accordance with energization of means subjecting a space closedby a flexible cube mold to vacuum and pressure conditions, a controlarrangement including: thermostatic means responsive to a temperaturecorresponding to a well-frozen condition of said ice to energize saidmeans for subjecting said space successively to a vacuum, pressure, andvacuum condition, and responsive to a temperature above freezingcorresponding to a supply of water of normal temperature to said mold todeenergize said means; reset heater means energizable to apply heat tosaid thermostat; switch means for controlling energization of said resetheater means; and means for operating said switch means to a positionenergizing said heater means only when said vacuum condition exists.